#14711 introduced some warnings when building with gcc compiler.
See:
This gcc issue has been known since version 4.6.0 and last updated in 2017. From the boost docs:
The default constructor of
optionalcreates an uninitializedoptionalobject.
Also: False positive with -Wmaybe-uninitialized (pointed out by @Empact)
This PR removes these warnings.
The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.
No conflicts as of last run.
Generally we don’t work around bugs in a compiler if they are only warning related and fixed in recent versions.
Which recent version of gcc do you mean?
I would prefer not to make these changes since I think they make the code less readable, are only applicable to older buggy versions of gcc, and just avoid warnings not errors.
But I will add my utACK 595b62fcf93aedc852dc93a7b5f112f11e50a5ef since the changes do look safe, and other people might want them.
I wonder what would happen if you tried to replace:
0Optional<int> height;
with:
0Optional<int> height = nullopt;
I think a change like that would be more readable.
According to the bug report, it was fixed in gcc6. I am using clang7.
I am using gcc 7.3.0 (both Linux Mint 19.1 and Ubuntu Bionic). Warnings are still present. @ryanofsky
Optional<int> height = nullopt;
I’ve tried this approach while working on this PR. nullopt did not help. Perhaps this is due to the lazy initialization inside boost::optional.
altheight and height are initialized. Not sure if this should be fixed or how.
I think “The default constructor of optional creates an uninitialized optional object.” may be misleading as default-constructed values are valid, e.g.. boost::optional has an is_initialized member that is false on default initialization, and just means the object is falsey.
Other thoughts:
I would prefer not to use auto here given there are plenty of numeric types.
I would access this functionality via src/optional.h, where the other boost::optional references are.
Incidentally here’s the doc where boost recommends this fix. No opinion on whether this should be fixed.
I’m using gcc 7.3.0 on my main development system so I see these scary warnings all the time, so I’d prefer for this to be merged or the relevant warning disabled (for that gcc).
Edit: tested that this makes the warnings disappear here.
40@@ -41,6 +41,8 @@
41
42 #include <functional>
43
44+#include <boost/optional.hpp>
optional.h, define our own make_optional like the Option<T> itself instead of boost appearing here direclty.
